running pmset -g assertions
gives me this:
pid 197(coreaudiod): [0x0001804100018074] 00:02:41 PreventUserIdleSystemSleep named: "com.apple.audio.AppleHDAEngineOutput:1B,0,1,1:0.context.preventuseridlesleep"
Created for PID: 12042 (this is the gideros player)
No sound is being played.
I don't know the details of how coreaudio is being used but I'm guessing you may need to adjust a flag or implement some sort of "if no audio has been playing in the past X seconds/minutes, shut off audio" logic.
It seems other apps (whats app, spotify) had the same issue reported by users and eventually fixed it so it must be a common issue.